FIR Filter function sample rate

Hello,

I have a problem with the use of the functions fir1() and fir2() in Matlab.

The bandpass example on the fir() page here https://de.mathworks.com/help/signal/ref/fir1.html#bulla9m shows, how to design a bandpass dependent on the normalized frequencys. So as far as I understood, the normalized frequenzy is . But what I can't find is, what sampling frequency has been used? For my filter design, I want to use a specific . How can I set this as a parameter for the functions, or what am I not understanding here?

In the filter designer app, it is also possible to specify the sampling frequency. But there, I have problems exporting the filter coefficiants to a vector in matlab

[Alexander Letzel]

If i needed a bandpass with a passband of 1000Hz to 2000Hz and have a =50000Hz, as an argument of the fir1() function, would I need to set the parameters to and ?

Answer 1

[Devineni Aslesha]

To design an FIR bandpass filter with a passband of 1000Hz to 2000Hz and fs=50000Hz, the passband frequency is given as normalized frequency in terms of window coefficients in multiples of pi.

b = fir1(48, [0.04 0.08]);

where 0.04*pi = 2*pi*1000/fs and 0.08*pi = 2*pi*2000/fs

Doc Link:

https://www.mathworks.com/help/signal/ref/fir1.html